Diversity and abundance of vascular epiphytes: a comparison of secondary vegetation and primary montane rain forest in the Venezuelan Andes

Species diversity of vascular epiphyte plant communities was studied in La Carbonera, a montane rain forest dominated by Podocarpaceae in the Venezuelan Andes. We compared the epiphyte communities of the primary, disturbed, and secondary forest areas of La Carbonera in order to augment the scarce knowledge on the effects of anthropogenic disturbance on these important elements of tropical vegetation. Diversity of vascular epiphytes (191 species in the whole forest area) was low in the disturbed and secondary areas (81 spp.) compared to adjacent primary forest (178 spp.). Four types of disturbed forest and secondary vegetation supported different numbers of epiphyte species, showing a decline with increasing degrees of disturbance (65 spp. along a road transect, 42 spp. on relict trees in disturbed forest, 13 spp. in a tree plantation and 7 spp. in a former clearing, both secondary vegetation units). Epiphytic species composition in primary and disturbed or secondary forest areas differed markedly: disturbed habitats harboured fewer fern and orchid species but more bromeliad species than the primary forest. Probably the families occurring only in primary forest sites of our study may be useful as bioindicators to determine the degree of disturbance in other habitats of mountain rain forests as well. Epiphyte abundance was also lower in disturbed habitats: a remnant emergent tree supported only about half as many epiphyte individuals as a member of the same species of similar size in the primary forest. The decrease in species numbers and abundance as well as the differences in species composition are mainly due to the less diverse phorophyte structure and less differentiated microclimate in the disturbed and secondary vegetation compared to the primary forest.     

Short-term impact of disturbance on genetic diversity and structure of Indonesian populations of the butterfly Drupadia theda in East Kalimantan

We investigated the short‐term impact of disturbance on genetic diversity and structure of the tropical butterfly Drupadia theda Felder (Lepidoptera: Lycaenidae). Populations were sampled from five landscapes in East Kalimantan (Borneo, Indonesia) which were differentially disturbed by selective logging and the 1997/1998 El Niño Southern Oscillation (ENSO)‐induced drought and fires. Sampling occurred before (in 1997) and after the forest fires (in 1998, 1999, 2000, and 2004). Drupadia theda populations underwent serious population size reductions following the 1997/1998 ENSO event. For a total of 208 individuals, we sequenced a 509‐bp segment of mtDNA containing the control region plus the 5’ end of the 12S rDNA gene. Haplotype diversity in D. theda populations ranged from 0.468 to 0.953. Just after the 1997/1998 ENSO event, number of recorded individuals and genetic diversity were very low in D. theda populations sampled in the two severely burned areas and in a small pristine forest fragment that was surrounded by burned forest and thereby affected by drought. Interestingly, higher levels of genetic diversity were observed in logged forest compared to proximate pristine forest. After 1998, the genetic composition within the three ENSO‐disturbed areas diverged. In the twice‐burned forest, the genetic diversity in 1999 already approached pre‐fire levels, while it remained nearly unchanged in proximate once‐burned forest. Our data suggest that the 1997/1998 ENSO‐induced drought and fires caused massive reductions in the genetic diversity of D. theda and that population recoveries were linked to their geographical position relative to patches of unburned forest (and thus to source populations).     

Forest Modification Affects Diversity (But Not Dynamics) of Speciose Tropical Pyraloid Moth Communities

We studied temporal and spatial dynamics of extremely diverse moth ensembles (Lepidoptera: Pyraloidea) along a gradient of forest disturbance ranging from undisturbed primary tropical rain forest to different kinds of modified forest and open cultivated land at the margin of Mount Kinabalu National Park (Sabah, East Malaysia). We sampled moths by light trapping during two periods (March‐May and August‐September 1997). We collected a total of 7724 individuals representing 680 species during 78 light‐trapping nights at six study sites. Species diversity (Fisher's α) of ensembles in undisturbed primary forest was distinctly higher than in disturbed or secondary forest. More pyraloid moths were attracted in undisturbed primary forest. Samples from disturbed primary or old‐growth secondary forest were statistically indistinguishable from the undisturbed primary forest ensemble in regard to species composition. Thus, pyraloid ensembles from disturbed forest with tall trees remaining appeared to represent impoverished subsets of the undisturbed primary forest community. The more heavily disturbed sites had a distinct fauna and showed a stronger faunal differentiation among each other. Four species of the genus Eoophyla, in which aquatic larvae feed on algae in fast‐running streams benefited prominently from forest disturbance. Temporal variation of ensembles was remarkably concordant across the disturbance gradient. Relative abundance variation of the commonest species was identical at all sites. Overall, pyraloid moths responded more sensitively to anthropogenic habitat alteration than most other moth taxa studied thus far in tropical regions and allowed for an analysis of diversity patterns at a high temporal resolution.     

On the structure of rodent communities in tropical forests of southern Vietnam

The abundance, species diversity, and spatial distribution of small mammals were studied in two localities in southern Vietnam: the Cat Tien National Park and the Binh Chau Nature Reserve. Rodents were trapped on the ground and in the tropical forest canopy (2–12 m above the ground), marked, and released on the spot. Species diversity of small mammals in undisturbed tropical forest (9 species) was higher than in disturbed tropical forest (14 species). The rat Maxomys surifer and the squirrel Callosciurus flavimanus were dominant. In undisturbed forest, the frequencies of rodent occurrence on the ground and in the canopy were of the same order; in disturbed forest, rodents occurred in the canopy an order of magnitude less frequently than on the ground.     

Abundance responses of frugivorous bats (Stenodermatinae) to coffee cultivation and selective logging practices in mountainous central Veracruz,Mexico

Shifting and permanent cultivation, selective logging, cattle production and coffee plantations are among the most important factors in montane cloud forest conversion and disturbance. Although shaded-coffee plantations can contribute to the preservation of local species richness, abundance of organisms could be determined by habitat resource availability in agricultural landscapes. We compared abundance of Sturnira and Artibeus bats (Phyllostomidae, Stenodermatinae), in shade coffee plantations and disturbed cloud forest fragments, which represent habitats with different chiropterochorous plant density. We also investigated the relationship between bat species abundance and food plant richness, abundance and diversity. We captured 956 bats, 76% in cloud forest fragments and 24% in shaded coffee plantations. Abundance of Sturnira spp. (small bats) was greater in cloud forest than in coffee plantations, but Artibeus spp. (large bats) abundance was similar in both habitats. Chiropterochorous plant abundance was positively related with bat abundance for Sturnira spp., while chiropterochorous plant richness and diversity were negatively related for Artibeus spp. This suggests that frugivorous bats with different morphological and ecological characteristics respond differentially to anthropogenic activities. For landscape management purposes, the maintenance and augmentation of diverse food resources, for frugivorous bats with different foraging requirements in coffee plantations, will benefit the resilience of bats to modification of their natural habitat.     

Comparison of Bird Communities in Primary vs. Young Secondary Tropical Montane Cloud Forest in Guatemala

Cloud forests in central Guatemala are fragmented and decreasing in area due to slash-and-burn agricultural activities. We studied bird species composition, abundance, guild composition, and site tenacity of a 102 ha plot located in a cloud forest region of the Sierra Yalijux in Guatemala, half of which was primary forest and half young secondary forest (<7-years-old). Of the 100 species present 14 were restricted to the Endemic Bird Area ‘Northern Central American highlands’ (i.e. 66% of a total of 21 endemics). Five of the 100 analysed species, including one of the restricted-range species (Troglodytes rufociliatus), had a significantly different abundance in primary and secondary forests. Theoretical analysis suggests that seven species out of a community comprised of 141 bird species are already extirpated and only three out of the 14 present restricted-range species might survive the current state of deforestation. Insectivores were the dominant guild on the plot in terms of numbers of species, followed by omnivores, frugivores and granivores. However, in terms of individuals, omnivores made up nearly half of the bird individuals in primary forest, but declined by 44% in secondary forest, whereas granivores more than doubled in this habitat type. Numbers of species per guild were not significantly different between habitats, while numbers of individuals per guild were significantly different. In general, individuals per species are significantly different in the two habitats. Results suggest that most of the species that are currently surviving in the remnant forests of the Sierra Yalijux might be fairly well adapted to a range of forest conditions, but that populations of a number of restricted-range species might be small. Even generalists species like the Common Bush Tanager (Chlorospingus ophthalmicus) are less abundant in secondary vegetation than in primary forest of the study plot.     

The Importance of Primary Tropical Rain Forest For Species Diversity: An Investigation Using Arboreal Ants as an example

The arboreal ant communities of a primary lowland rain forest and three differently disturbed forests that lie close together forming an anthropogenic disturbance gradient were collected with insecticide fogging. Combined samples from all trees (87 foggings) comprised 153,504 ants sorted to 331 morphospecies. The primary forest ant fauna was characterized by high species richness and 53 foggings were necessary to collect communities representatively. Another 63 species of ants were found in the disturbed forests indicating a large regional species pool that might exceed 420 species of arboreal ants. Anthropogenic disturbance caused a change in the taxonomic composition, diversity and structure of ant communities. Community size was a predictor of species richness in the severely disturbed forest types but not in the old secondary or primary forest. Ant abundance had declined significantly in the disturbed forests and only 10% of the primary forest’s species were collected in the most disturbed forest type. In each of the secondary forests a change in the frequency distribution of species was observed and a small number of species had gained numerical dominance. Analysis of species associations indicates that the strength of species interactions changed with the degree of forest disturbance. These changes were still clearly recognizable after 40 years of forest regeneration despite optimal conditions for colonization from the adjacent primary forest, demonstrating that the time scale needed for forest recovery after anthropogenic disturbance is very long.     

Population densities of Sulawesi crested black macaques (Macaca nigra) on Bacan and Sulawesi,Indonesia: Effects of habitat disturbance and hunting

Population surveys of Sulawesi crested black macaques (Macaca nigra) were conducted on the Indonesian islands of Sulawesi and Bacan in 1992–1994 to assess the status of natural populations and determine habitat and anthropogenic factors affecting their population densities. We surveyed five sites for primates, including undisturbed and disturbed habitats. Data were collected on habitat structure and composition at two undisturbed and one disturbed forest site in which the primates were surveyed. The highest density of macaques was found in primary forest at Gunung Sibela Nature Reserve on Bacan (170.3 individuals/km²). Population density in logged forest on Bacan was high but significantly less than primary forest (133.4 individuals/km²). The high density of crested black macaques in primary forest on Bacan is best explained by the high carrying capacity found in primary forest. The lower food quantity and quality of food resources found in logged forest correlated with lower primate densities compared to primary forest. However, the large population of macaques in logged forest demonstrates the conservation value of such forest. Densities on Sulawesi at Tangkoko-Batuangas-DuaSudara Nature Reserve (TBDS) showed a continuing decline since earlier surveys. Primate densities were highest near the protected center of Tangkoko Reserve (66.7 individuals/km²). The peripheral areas of Batuangas and DuaSudara, even though adjacent and continuous, showed lower population densities of 46.4 and 23.5 individuals/km², respectively. The best explanation for the continued decline of Macaca nigra populations at TBDS is hunting. Unless conservation measures are implemented immediately, M. nigra on Sulawesi risks extinction in the near future. Am. J. Primatol. 44:89–106, 1998. © 1998 Wiley-Liss, Inc.     

Sexual Dimorphism in Development of Kidney Damage in Aging Fischer-344 Rats

BackgroundAging kidneys exhibit slowly developing injury and women are usually protected compared with men, in association with maintained renal nitric oxide.ObjectivesOur purpose was to test 2 hypotheses: (1) that aging intact Fischer-344 (F344) female rats exhibit less glomerular damage than similarly aged males, and (2) that loss of female ovarian hormones would lead to greater structural injury and dysregulation of the nitric oxide synthase (NOS) system in aging F344 rat kidneys.MethodsWe compared renal injury in F344 rats in intact, ovariectomized, and ovariectomized with estrogen replaced young (6 month) and old (24 month) female rats with young and old intact male rats and measured renal protein abundance of NOS isoforms and oxidative stress.ResultsThere was no difference in age-dependent glomerular damage between young or old intact male and female F344 rats, and neither ovariectomy nor estrogen replacement affected renal injury; however, tubulointerstitial injury was greater in old males than in old females. These data suggest that ovarian hormones do not influence these aspects of kidney aging in F344 rats and that the greater tubulointerstitial injury is caused by male sex. Old males had greater kidney cortex NOS3 abundance than females, and NOS1 abundance (alpha and beta isoforms) was increased in old males compared with both young males and old females. NOS abundance was preserved with age in intact females, ovariectomy did not reduce NOS1 or NOS3 protein abundance, and estrogen replacement did not uniformly elevate NOS proteins, suggesting that estrogens are not primary regulators of renal NOS abundance in this strain. Nicotinamide adenine dinucleotide phosphate oxidase-dependent superoxide production and nitrotyrosine immunoreactivity were increased in aging male rat kidneys compared with females, which could compromise renal nitric oxide production and/or bioavailability.ConclusionsThe kidney damage expressed in aging F344 rats is fairly mild and is not related to loss of renal cortex NOS3 or NOS1 alpha.     

Links between the Environment,Abundance and Diversity of Andean Moths

Ideas on the spatial variation of biodiversity often imply a causal link between the abundance and species richness of organisms. We investigated this ‘more individuals hypothesis’ using light‐trapping data of three unrelated groups of moths (Arctiidae, Geometridae and Pyraloidea) from the Ecuadorian Andes. We analyzed environmental correlates of specimen densities found in different habitats, finding effects of temperature, moonlight, forest succession, elevation and season. We corrected abundance data for light‐trapping artefacts, and we measured species diversity with various metrics known to be unbiased by undersampling. We found significant positive correlations between abundance and species diversity for all three taxonomic groups. We discuss implications for a general evaluation of species‐energy theory as well as for a better understanding of ecological processes in montane habitats of the Andes.     

The influence of anthropogenic disturbances on the structure of arboreal arthropod communities

In the framework of our research, aimed at understanding the processes structuring tropical arthropod communities, we investigated the changes occurring in tree crown communities of forests of different disturbance levels. These were a mixed dipterocarp primary lowland rain forest in Kinabalu National Park (in Sabah, Malaysia) and, some kilometres away, three forests of regeneration periods 5, 15, and 40 years following a clear-cut. These disturbed forest sites were adjacent to one another and merged into mature forest. From each forest at least ten individuals of one tree species were sampled using the fogging method. In the primary forest relative proportions of some arthropod taxa differed on the ordinal and familial level significantly within trees. The dominance of Formicidae was characteristic as was the almost complete lack of less mobile arthropods such as Lepidoptera larvae. In the five-year- old forest, differences in relative proportions among most taxa had almost disappeared. Formicidae abundances had declined drastically which coincided with an increase of Lepidoptera larvae. With progressing forest succession, arthropod communities increasingly converged on the pattern of primary forest, and total ant abundance as well as diversity increased significantly. Ant communities in the most disturbed forest were of low structural complexity, and to a large degree predictable in species arrangement, but became more and more unpredictable as the complexity of the forest increased. Several species of Coleoptera and non-formicine Hymenoptera occurred in high numbers in the youngest forest, contrasting with the mature forest where all species were typically rare. These changes may indicate a change in the structuring mechanisms from predominantly deterministic processes in disturbed forests to stochastic processes in mature forest.     

Seasonal changes of reproductive behavior and fecal steroid concentrations in Père David's deer.

From July 1997 to September 1997 and from March 1998 to July 1998, we studied reproductive behaviors of Père David's deer in Dafeng, China. During the field behavioral observations, we collected fresh voided fecal samples from the Père David's stags and hinds periodically and kept those samples under -20 degrees C until laboratory analysis. We analyzed the fecal testosterone, estradiol, and progesterone concentrations in those samples using radioimmunoassay. During this study, we also recorded 17 types of male reproductive behaviors and nine types of female reproductive behaviors. Reproductive behaviors and the fecal steroid concentrations showed overt seasonal fluctuations. There were statistically significant correlations between some male reproductive behaviors, such as anogenital sniffing, urine sniffing, urine spraying, wallowing, bellowing, antler adorning, Antler swags mud, chasing, herding hinds, chin resting, mounting and copulating, with the fecal testosterone concentrations. These results suggested that seasonal reproductive behaviors in stags are strongly associated with circulating testosterone. We also found that some female reproductive behaviors fluctuate corresponding with changes in fecal estrogen concentrations. Although there was no direct evidence to confirm the correlations between female reproductive behaviors and fecal estrogen in our experiment, we could not rule out that reproductive activities of hinds were largely related to ovarian estrogen secretion, and estrogen is necessary for inducing female reproductive behaviors.     

Seed size: a key trait determining species distribution and diversity of dry tropical forest in northern India

The study examined the relationships among seed size, plant distribution and abundance in a dry tropical forest of northern India. Results indicated that small-seeded species, which were generally wind-dispersed, were more widely distributed, at this local scale, compared to large-seeded species. However, the proportional abundance and basal cover of seed size categories indicated that the structure of the dry forest was largely determined by the medium- to large-seeded species. There was a considerable amount of redundancy within each seed size group, which added to the species diversity. Variability in seed size and the variable degree of shade-tolerance permit the species to occupy the full range of the gradient of light environments of the forest floor. This study revealed that in little to moderately disturbed locations seedlings of large-seeded species increased in abundance, whereas in extremely perturbed locations seedlings of species with medium-sized to small seeds were more abundant.     

Microbiological diagnostics of soil stage in the phyllosphere of the woodland ecosystem of Siberia

It is shown that the diagnostics of the stage of woodland soils affected by wildfires and forest cuts can be determined by the evaluation indexes of the range of the scale of abundance of typical ecologic-and-trophic groups of microorganisms (ECTGM), microbiological activity coefficients, reserve and abundance fluctuations, and metabolism. The degree of impact of the technogenic emissions on the forest cover, soil, and phyllosphere according to ECTGM abundance on the diagnostic environments and their fermentative activity is expressed with the help of an advisability functional relation.     

Small montane cloud forest fragments are important for conserving tree diversity in the Ecuadorian Andes

Montane tropical cloud forests, with their complex topography, biodiversity, high numbers of endemic species, and rapid rates of clearing, are a top global conservation priority. However, species distributions at local and landscape scales in cloud forests are still poorly understood, in part because few regions have been surveyed. Empirical work has focused on species distributions along elevation gradients, but spatial variation among forests at the same elevation is less commonly investigated. In this study, the first to compare tree communities across multiple Andean cloud forests at similar elevations, we surveyed trees in five ridge‐top forest reserves at the upper end of the ‘mid‐elevation diversity bulge’ (1900–2250 masl) in the Intag Valley, a heavily deforested region in the Ecuadorian Andes. We found that tree communities were distinct in reserves located as close as 10 to 35 km apart, and that spatially closer forests were not more similar to one another. Although larger (1500 to 6880 ha), more intact forests contained significantly more tree species (108–120 species/0.1 ha) than smaller (30 to 780 ha) ones (56–87 species/0.1 ha), each reserve had unique combinations of more common species, and contained high proportions of species not found in the others. Results thus suggest that protecting multiple cloud forest patches within this narrow elevational band is essential to conserve landscape‐level tree diversity, and that even small forest reserves contribute significantly to biodiversity conservation. These findings can be applied to create management plans to conserve and restore cloud forests in the Andes and tropical montane cloud forests elsewhere.     

Ecophysiology and genetic diversity in species of the bamboo Chusquea in the high Andes,Venezuela

ABSTRACT

Background: Woody bamboos of the genus Chusquea grow along a broad range of elevations in the Venezuelan Andes. Their growth-form and density vary along the cloud forest – páramo gradient. In this article, we related ecophysiological traits and population genetic diversity information to explain the distribution of growth-form patterns of Chusquea in the Merida Andes, Venezuela.

Aims: We quantified differences in the ecophysiological response and genetic diversity of scandent cloud forest and shrub-like páramo bamboos of the genus Chusquea, taking in account the differences in their flowering patterns, growth-form and habitat.

Methods: We related low temperature resistance, water relations and leaf gas exchange variables to the growth-form, habitat, flowering patterns and genetic diversity in species of Chusquea. The genetic diversity study was based on Inter Sequence Simple Repeats and Random Amplified Polymorphic DNA markers analysis of cloud forest and páramo populations.

Results: Scandent cloud forest and shrub-like páramo species of Chusquea had a very similar ecophysiological response for all the variables analysed during wet and dry seasons and were capable of enduring freezing temperatures through moderate supercooling. Species associated with the cloud forest – páramo gradient maintained low stomatal conductance and transpiration rates that favoured high leaf water potentials, without limiting photosynthetic rates. Shrub-like bamboos growing above the continuous forest line had a small decline in net photosynthesis rates, associated with an increase in water use efficiency. Both scandent and shrub-like bamboos had a remarkably high genetic diversity, comparable to non-clonal species.

Conclusions: Species of Chusquea in the Venezuelan Andes are a physiologically relatively homogeneous group across a broad elevation gradient. Population genetic diversity appears to be more related with their flowering pattern and habitat conditions than with their growth form.     

Negative effects of urbanisation on the physical condition of an endemic dung beetle from a neotropical hotspot

1. Urbanisation causes important losses in biodiversity and ecosystem of animals. To test whether these negative effects are preceded by unhealthy individuals in urban populations, we evaluated the effects of urbanisation on the abundance and physical condition of the dung beetle Dichotomius guaribensis, an endemic species of the Brazilian Atlantic Forest. 2. We sampled beetles in nine forest fragments with different urbanisation degrees, embedded in the urban matrix of the city of João Pessoa. Besides testing the abundance in each fragment, we quantified four indicators of physical condition in males and females: body size, body mass, energetic condition, and mite load. 3. Females tended to be larger, and to have less lipid mass and more mites than males. Urbanisation had no effect on beetle abundance, but it negatively affected body mass and lipid content in males, but not females, revealing different sensitivities for both sexes. Body size and mite load were not affected by urbanisation in males or females. Fragment size had no effect on beetle abundance and physical condition in both sexes, suggesting that urbanisation has a greater impact than fragment size on beetle individual condition. 4. In this study, we show that individual deterioration precedes population declines in disturbed environments, and our study opens new insights into the proximate causes that leads to the loss of biodiversity and ecosystem services in urbanised regions.     

Axinaea fernando‐cabiesii and A. reginae spp. nov. (Melastomataceae) from upper Amazonia of Peru,with notes on the conservation status of A. flava

Two new Peruvian species of Axinaea (Melastomataceae) are described. Axinaea francisco‐cabiesii and Axinaea reginae are small trees, endemic to the cloud forest zone in the northern Andean region of Peru. The border region of Peru and Ecuador is one of the Earth's most biologically diverse areas. The Huancabamba depression of the central Andean Cordillera allows for dispersal of flora and fauna between the Amazon Basin and the Pacific lowlands. Additionally, the region is characterized by a fast transition between the humid mountain forests of the northern Andes and the dry, deciduous forests of the northern Peruvian lowlands, making it a hotspot for endemic species. Field observations indicate that both new Axinaea species have small population sizes, occurring in a very restricted habitat. Axinaea flava was described only a few years ago from the cloud forest – paramo transition zone in southernmost Ecuador between 3400 and 3800 m a.s.l. This small tree is the only yellow‐flowered species of the genus. The original assessment counted about 100 individuals. In the last decade, livestock grazing and widespread burning have intensified in the region, and a new assessment yielded only 10 individuals, four of which were damaged by fire. This puts the species in danger of extinction. We encourage search for other populations in southern Ecuador and northern Peru.     

西双版纳片断热带雨林的结构、物种组成及其变化的研究

通过对西双版纳地区的６个“龙山”片断热带雨林与同样类型的原始热带雨林的比较研究,探讨了片断热带雨林的群落结构、种类组成、生活型构成、种群结构、植物丰富度及多样性等的变化及其规律。随着热带雨林的片断化,森林边缘效应和人为干扰加剧,热带雨林群落的结构变得不完整,植物丰富度降低。在生活型构成上,附生植物,大、中高位芽植物以及地上芽植物比例减少,藤本植物和小高位芽植物比例明显增高。在种群结构上,受轻、中度干扰的片断雨林,仅含１～２个个体的种类在群落中的相对数量有所增加,乔木种类组成变得不稳定,随着人为干扰的加剧,那些仅有１～２个个体为代表的种类将首先消失。在单位面积种数和物种多样性指数上,情况比较复杂,热带雨林片断化和受到一定干扰可能会增加藤本植物多样性指数,但干扰过度又会减低其多样性指数,附生植物多样性指数则随干扰和隔离时间呈明显下降趋势,但总的说来,片断热带雨林单位面积上的种数远比原始林少得多,随着人为干扰和隔离的加剧,物种多样性指数显著降低。     

Ecology of Nectomys squamipes, the neotropical Water rat, in central Brazil: home range, habitat selection, reproduction and behaviour

Relatively few studies have examined the ecology of small mammals of South American tropical forests. The ecology of the neotropical Water rat, Nectomys squamipes , was investigated in gallery forest in central Brazil during a 14-month mark-recapture study. A total of 11 male and 10 female Water rats were captured; minimum number of animals known alive per month varied from one to four per hectare. Home range size for individuals captured eight or more times was 0.3–1.6 ha. Water rats were captured almost exclusively near the stream or in other inundated portions of the forest. Distance to water, soil moisture, number of tree ferns, number of trees, exposed tree-root cover, and litter cover on the ground were among the variables important in defining microhabitat of N. squamipes. At least some males were in breeding condition (testes scrotal) during all months; females were in breeding condition (vagina perforate) most of the year, but pregnancies were noted only in August, October and November. Captive Water rats consumed plant matter, insects (Blattidae, Gyrinidae, Scarabeidae), tadpoles and small fish. Aquatic prey items were located by searching movements of the forepaws. Water rats demonstrated agility in both climbing and swimming. Physiological dependence of N. squamipes on water is suggested by capture sites and observations of drinking in captive animals.